Near degeneracy between two quantum states is usually associated with fundamental symmetries and symmetry breakings in complex many-body systems like atomic nuclei.Pseudospin symmetry was introduced to describe energy...Near degeneracy between two quantum states is usually associated with fundamental symmetries and symmetry breakings in complex many-body systems like atomic nuclei.Pseudospin symmetry was introduced to describe energy degeneracy between single-particle states with quantum numbers(n,l,j=l+1/2)and(n-1,l+2,j=l+3/2)[1-3].展开更多
Backbending played a pivotal role in the progress of high-spin structure research[1].This phennomenon was interpreted as a result of band-crossing between two intrinsic configurations which dominate lower-and higher-s...Backbending played a pivotal role in the progress of high-spin structure research[1].This phennomenon was interpreted as a result of band-crossing between two intrinsic configurations which dominate lower-and higher-spin region.Usually the two configurations are differed by two nucleons,which are paired in the former,and unpaired in the latter.According to the strong-coupling scheme,two unpaired quasi-particles can couple to both high-K and low-K configurations in deformed nuclei.Usually only the lower can be identified experimentally since it is favoured by the Gallagher-Moszkowski spin-spin coupling rules[2].展开更多
Isomeric I^(π)=8^(-) states have been observed in the even-even N=74 nuclei ^(138)Gd[1],^(136)Sm[2],^(134)Nd[3],^(132)Ce[4],^(130)Ba[5],^(128)Xe[6]with half-lives ranging from nanoseconds(Xe)to milliseconds(Ba,Ce).Ro...Isomeric I^(π)=8^(-) states have been observed in the even-even N=74 nuclei ^(138)Gd[1],^(136)Sm[2],^(134)Nd[3],^(132)Ce[4],^(130)Ba[5],^(128)Xe[6]with half-lives ranging from nanoseconds(Xe)to milliseconds(Ba,Ce).Rotational bands built on the K^(π)=8^(-) isomer were identified in all these isotones,with the exception of 130Ba.The singleparticle configuration of the isomers have been deduced from theΔI=2 toΔI=1γ-ray intensity branching ratios,which allowed to extract the(gKgR)/Q0 values,and therefore the quasi-particle configuration of the state.展开更多
The low-lying excitation energies of the 2_(1)^(+),4_(1)^(+),2_(2)^(+),0_(2)^(+),3_(1)^(-),0_3^(+)states in even-even nuclei are studied using two modern machine learning algorithms:the Light Gradient Boosting Machine...The low-lying excitation energies of the 2_(1)^(+),4_(1)^(+),2_(2)^(+),0_(2)^(+),3_(1)^(-),0_3^(+)states in even-even nuclei are studied using two modern machine learning algorithms:the Light Gradient Boosting Machine(LightGBM)and Sparse Variational Gaussian Process(SVGP).The obtained results demonstrate that both LightGBM and SVGP perform well on the training and validation datasets when informed by a physics-based feature space.A detailed comparison of the results obtained for 2_(1)^(+)and 2_(2)^(+)states using the Hartree-Fock-Bogoliubov theory extended by the generator coordinate method and mapped onto a five-dimensional collective quadrupole Hamiltonian shows that both ML algorithms outperform this model in terms of accuracy.The extrapolation capabilities of these algorithms were further validated using newly measured 12 data points of 2_(1)^(+)and 2_(2)^(+)states,which were not included in the training set.In addition,the partial dependence plot method and the Shapley additive explanations method are used as interpretability tools to analyze the relationship between the input features and model predictions.These tools provide in-depth insights into how the input features influence the prediction of low-lying excitation energies and help identify the most important features that drive the prediction,which are valuable for understanding the low-lying excitation energies.展开更多
文摘Near degeneracy between two quantum states is usually associated with fundamental symmetries and symmetry breakings in complex many-body systems like atomic nuclei.Pseudospin symmetry was introduced to describe energy degeneracy between single-particle states with quantum numbers(n,l,j=l+1/2)and(n-1,l+2,j=l+3/2)[1-3].
文摘Backbending played a pivotal role in the progress of high-spin structure research[1].This phennomenon was interpreted as a result of band-crossing between two intrinsic configurations which dominate lower-and higher-spin region.Usually the two configurations are differed by two nucleons,which are paired in the former,and unpaired in the latter.According to the strong-coupling scheme,two unpaired quasi-particles can couple to both high-K and low-K configurations in deformed nuclei.Usually only the lower can be identified experimentally since it is favoured by the Gallagher-Moszkowski spin-spin coupling rules[2].
文摘Isomeric I^(π)=8^(-) states have been observed in the even-even N=74 nuclei ^(138)Gd[1],^(136)Sm[2],^(134)Nd[3],^(132)Ce[4],^(130)Ba[5],^(128)Xe[6]with half-lives ranging from nanoseconds(Xe)to milliseconds(Ba,Ce).Rotational bands built on the K^(π)=8^(-) isomer were identified in all these isotones,with the exception of 130Ba.The singleparticle configuration of the isomers have been deduced from theΔI=2 toΔI=1γ-ray intensity branching ratios,which allowed to extract the(gKgR)/Q0 values,and therefore the quasi-particle configuration of the state.
基金supported by the National Natural Science Foundation of China(12305128)the Hubert Curien Partnership(PHC)Cai Yuanpei Project+3 种基金the International Partnership Program of Chinese Academy of Sciences for Future Network(016GJHZ2023024FN)the Gansu Natural Science Foundation(24JRRA038)the Major Science and Technology Projects in Gansu Province(24GD13GA005)National Key R&D Program of China(2023YFA1606402)。
文摘The low-lying excitation energies of the 2_(1)^(+),4_(1)^(+),2_(2)^(+),0_(2)^(+),3_(1)^(-),0_3^(+)states in even-even nuclei are studied using two modern machine learning algorithms:the Light Gradient Boosting Machine(LightGBM)and Sparse Variational Gaussian Process(SVGP).The obtained results demonstrate that both LightGBM and SVGP perform well on the training and validation datasets when informed by a physics-based feature space.A detailed comparison of the results obtained for 2_(1)^(+)and 2_(2)^(+)states using the Hartree-Fock-Bogoliubov theory extended by the generator coordinate method and mapped onto a five-dimensional collective quadrupole Hamiltonian shows that both ML algorithms outperform this model in terms of accuracy.The extrapolation capabilities of these algorithms were further validated using newly measured 12 data points of 2_(1)^(+)and 2_(2)^(+)states,which were not included in the training set.In addition,the partial dependence plot method and the Shapley additive explanations method are used as interpretability tools to analyze the relationship between the input features and model predictions.These tools provide in-depth insights into how the input features influence the prediction of low-lying excitation energies and help identify the most important features that drive the prediction,which are valuable for understanding the low-lying excitation energies.
